Compensating axial thrust in multistage turbines



I K. RUDER. I COMPENSATING AXIAL THRUST IN MULTISTAGE TURBINES.

APPLICATION FILED MAY 13. 19t5.

1,347,59 1 Patented July 27, 1920,

UNITED sTATEs' PATENT OFFICE.

KARL 36mm, or MiiLHEI -RUHR, GERMANY.

COMPENSATING AXIAL THRUST IN MULTISTAGE TURBINES.

Application filed May 13, 1915.

To all whom it may concern Be it known that I, Knnn Ronnn, a citizen of the German Empire, residing at Miilheim-Ruhr, Germany, have invented a certain new and useful Improvement in Means for Compensating Axial Thrusts in Multi-' stage Turbines, of which the following is a specification.

My invention relates to means for compensating or balancing axial thrust in multistage turbines driven by steam, compressed air and similar media.

In the prior art, compensating means, as above referred to, haye been provided in multi-stage turbines by equipping the rotatory member with graduated or stepped heads having surfaces for receiving steam pressures, the arrangement being-such that the pressure upon each individual head, re solved axially, compensates for the axial thrust due to the action of the driving medium upon a corresponding stage or blade system of the turbine. As thus arranged, the particular head which, cooperatively with a suitable non-rotatory part of the turbine, serves to close off the lowest steam pressure of the several stages with respect to vacuum (or exhaust), also serves to balance the thrust due to said lowest steam pressure (pressure stage) and, hence, has the greatest diameter; and this entails various disadvantages. Thus, a large diametered head is costly and awkward to construct and structurally dangerous to operate. Moreover, such a head results in rather large steam losses, a matter of substantial importance because the difference between the steam pressure of the lowest stage and vacuum (or exhaust) corresponds to a considerable difference of heat and because, furthermore, the escaping steam passes into the exhaust instead of, as in the ,case of the higher steam pressure stages,

into a lower pressure blade system.

The present invention is an improvement upon the above referred to arrangement of stepped heads and contemplates such an arrangement and construction of the heads that the one which closes off the lowest steam pressure with respect to vacuum (or exhaust) will have the smallest diameter. In order to effect this result, the other head or, if there is a plurality of other heads, at least one of such heads, is so dimensioned that the steam pressure integrated there over will exceed the axial pressure due to Specification of Letters Patent.

Patented July 27, 1920.

Serial No, 27,958.

the action of steam upon the corresponding blade system and will be exerted in a direction-opposed to the axial pressure due to said blade system.-

T he structural arrangement actually employed and by means of which the appropriate balancing head closes off is, in the preferred form of the invention about to be described, a peripheral labyrinth packing of usual type placed between the head and the casing which surrounds it.

The invention will be better understood by referring to the accompanying diagrammatic drawings in which Figure 1 represents a preferred form thereof as applied to a two-step or two-stage turbine; and Fig. 2 represents a modified form of the invention as applied to such a turbine. The particular type of turbine represented is one in which a velocity turbine and reaction turbine are combined.

In Fig. 1, a represents the velocity wheel, while 6 and 0 represent, respectively, the intermediate and low pressure reaction drums or blade system. Balancing heads (Z and e are attached to andconstitute a part of the rotatory system. Head d, which is provided peripherally with a labyrinth packing d, and is adjacent to the blade system should have its diameter so chosen that not only shall the entire axial thrust to the right of the reaction elements 6 and c and of the wheel a be balanced or equalled by the pressure to the left over the annular surface 9; but there shall also be thereby produced an excess or preponderating pressure toward the left, thus making it possible and necessary to give the second balancing head 6 a smaller diameter in order to pro vide an annular surface it with suflicient area to neutralize said preponderance when acted upon by a suitable steam pressure sourcein this instance by the steam pressure acting on the low pressure reaction drum 0. For this purpose the space or chamber formed between the heads 03 and e and the turbine casing is joined by a pipe f with the steam space at the inlet end of drum 0. Head 0 is also provided with a peripheral labyrinth packing d", so that this particular head constitutes the closure against vacuum (or exhaust).

It is obvious that, as described, compensation will be complete at all times irrespective of equal changes of the inlet and exhaust pressures.

In the embodiment represented in Fig. 2, the head 6 is situated in the exhaust space instead of being adjacent'to the high pressure end of the turbine as in Fig. 1. This construction makes it possible to dispense with the pipe 7 since the pressure at the inlet end of low pressure reaction drum 0 may be readily transmitted to the annular sur face it (corresponding to the surface 7b of Fig. 1) by merely placing steam ports or openings 2' in the end of drum 0. 7

It is to be noted that in both embodiments illustrated the arrangement is such that the head of smallest diameter cooperates with the casing to close off or isolate the exhaust passage or chamber, that is to say, to prevent the passage of fluid past such head into or from the exhaust chamber or passage.

Having described my invention, I claim:

1. In a multi-stage elastic fluid turbine havinga separate blade carrying drum for each stage, a casing, a shaft carrying said I drums, and a plurality of balancing heads of different diameters also carried by said shaftythere being as many heads as there are drums, one of said heads being adapted to receive a preponderating steam pressure ing with a part of the casing to close oil the exhaust passage.

2. In a multi-stage elastic fluid turbine having a separate blade carrying drum for each stage, a casi'ng, a shaft carrying said drums, and a plurality of balancing heads otdiflerent diameters also carried by said shaft, there being as many heads as there are drums, one of said heads being adapted to receive a preponderating steam pressure upon one side tending to move the shaft in a direction opposite to that in which the driving fluid tends to move it, and means for applying a lower steam pressure to the opposite side of saidnhead, the smallest head cooperating with a part of the casing to close off the exhaust passage.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses' V KARL RODER. [11. s] Witnesses:

HELENVNUFER, ALBERT NU'FER. 

